We’re over visiting with a friend (Colin Doughan of the Space Business Blog fame) on the way down to LA, and decided to use his internet connection to upload our highlights video from the flight yesterday:
[Update 5/25/11: We realized after the flight that we hadn’t gotten waivers to show the faces of the other passengers on the plane, so we had Brandon Seifert help us blur their faces, put in credits at the front, and the back of the film. The film shows the same parabolas, but the faces were blurred to protect the privacy of the other people on the plane. The old video is being pulled. If you’ve linked to this video, the above link will take you to the new video.]
So what’s next?
Congratulations! From the looks of this test, it does seem like a bit of a challenge to get it to evenly attach given how easy it is to push around the target object in zero gee. Have you considered trying to have the center pads attach first and have some sort of tension sensor that reports whether it has a lock then have that trigger a rapid fold and grip response in the larger edge pads which can benefit from the fact that the center grip gives them something to push against as they lay up against the object.
Yeah, getting good contact in such a short period of time with a low inertia object like this with completely manual control is really hard. We knew going into this test that this was an “acid test” that was a lot harder than what the sticky boom would actually be experiencing in space.
For the actual MSR mission:
1-The target would’ve been 5kg, not .75kg (more inertia makes it easier)
2-The whole system would’ve been servo controlled with relative position/velocity feedback, contact detection, and maybe joint angle detection, allowing a much more controlled contact profile.
3-You have tons of time, not just ~15s (of which a good chunk is spent just standing up and getting your position ready for the ball toss)
For most space missions, you’re latching onto things that mass in the 100s to 1000s of kg, so you have a lot more inertia so you can “push harder” during the contact phase.
Hope that all makes sense.
@Ed, I suspect what’s next is recovery from the sprint.
Congratulations to you and your whole team for a tough job well done.
Wow that looked frustrating. I had no idea the free-fall intervals were so short.
(At least you gained a new element for your next bad dream. FEET DOWN FEET DOWN.)
Actually the Zero-G people were a ton of help. They did a great job of keeping passengers out of our test area for the most part (we only had three times that people drifted in before we had a shot at running our experiment). It takes some getting used to, but we had a great time and got some good data.
Congrats, Jon (& team)
What is your target object? An 0.75 kg aluminized plastic ball?
What kind of force is the gripper generating?
There is remarkably little time to work in each parabola.
The main thing was that in the 1g tests, we always had something holding the ball, so you could easily conform the pads, lock it slowly, and then lift. In zero-G, getting the timing right with enough force to conform the gripper, locking it before it can bounce out, etc was really tricky to do manually. Future tests will likely have some automation of the capture process–had this been servo-controlled, we probably would’ve nailed it every time.
We took the first two parabolas to practice our experiment a little bit, but on the second lunar parabola Mike Judson told me “better do something crazy this time or you’re going to be kicking yourself”. So I did a full back flip. It was pretty cool. 🙂